The present specification relates generally to the field of displays. More particularly, the present specification relates to a method of and an apparatus for achieving two or more modes in a visual display.
In general, it is desirous to utilize filters in display technology to attenuate or accentuate particular types of electromagnetic radiation. For example, certain displays and visual equipment may desire to accentuate particular colors in the visible light spectrum and attenuate other colors in the non-visible and the visible light spectrum. Accordingly, these displays can utilize filters to provide accentuation and attenuation.
In one particular exemplary application, filters are utilized to adjust the dimming range of a backlight system in the display. In this way, filters are employed to selectively attenuate the lighting provided from the display. The attenuation serves to increase the visibility of information provided on the display over a variety of lighting conditions.
In another particular exemplary application, displays and other equipment utilized in military, sports and transportation activities are often employed in tandem with night vision equipment. These displays and equipment conventionally utilize a filter to accommodate the night vision equipment. Issues related to the use of displays and night vision equipment are described below with reference to an aviation application, although the below-mentioned issues are relevant to any applications of displays requiring attenuation or accentuation.
Certain aviation displays are color displays that are utilized with night vision imaging systems (NVIS). These displays provide visual information to captains, pilots, and drivers of ships, aircraft, and vehicles. The user of the color display often wears NVIS goggles at the same time he or she observes information from the color display.
Conventional NVIS goggles are sensitive to light in the infrared, near infrared and visible red spectrum (wavelengths of light). NVIS goggles are typically sensitive to light between 600 nm and 950 nm wavelengths. Although the NVIS goggles allow the pilot or person wearing the goggles to see objects which cannot ordinarily be seen by the naked eye, the goggles emit bright light (e.g., bloom effect) to the pilot""s eyes if the goggles are exposed to broadband emissions. Accordingly, if avionic displays emit infrared, near infrared and sometimes even visible red light, the pilot""s vision through the goggles is impaired when he or she views flight instrumentation provided on such avionic displays.
The bloom effect is undesirable for several reasons. First, the bloom effect prevents the wearer from seeing anything during the period in which the goggles emit the bright light. Second, when the goggles emit the bright light, the pilot""s eyes lose their night adaptation (e.g., night vision). Restoring night adaptation can take several minutes. Third, the night vision goggles may require a certain amount of time to be reset after a bloom effect event. Accordingly, the bloom effect is undesirable when operating a vehicle or aircraft in night vision conditions.
Conventional avionic displays designed to be utilized with NVIS equipment generally are restricted to a narrow emission, such as, single color (e.g., green) displays. The narrow emission is chosen so that it does not interfere with NVIS equipment. However, the restriction to the narrow emission significantly reduces the readability of information and the symbology provided on the displays. Further, it is difficult to highlight and differentiate large amounts of information on the display if the display is restricted to a single color.
Other conventional avionic systems have included color displays that include an NVIS filter. The color display operates in two modes, an NVIS mode (e.g., low luminance) and a daylight mode (e.g., full color capability). Each mode utilizes a distinct light path. The NVIS filter is provided between a light source used in the NVIS mode and an optical shutter, such as a liquid crystal display. The filter prevents emissions that cause NVIS equipment to bloom.
In the daylight mode, the displays use a second light source to provide light directly through the optical shutter without traversing the filter. The second light source is positioned so that its light is not provided through the NVIS filter.
The use of two light sources and two distinct light paths is expensive and adds to the overall size of the display. Each light path often requires duplicative components. Light sources, particularly avionic light sources, are expensive.
Thus, there is a need for a multi-mode display system that does not require multiple light sources. Further, there is a need for a display system which utilizes an integrated light path. Further still, there is a need for a compact display system which can utilize an NVIS or other filter. Further still, there is a need for an avionic display which requires a single light source for daytime and NVIS operation.
An exemplary embodiment relates to a display. The display includes a light source. The display comprises an electronically controlled mirror and a filter. The display provides light through the filter when the electronically controlled mirror is in a first mode. The light from the display is not provided through the filter when the electronically controlled mirror is in a second mode.
Another exemplary embodiment relates to an avionic display system. The avionic display system includes a light source, a filter and an electronically controlled mirror. The filter is positioned to receive light from the light source when the electronically controlled mirror is in a first mode. The electronically controlled mirror prevents light from reaching the filter in a second mode of operation.
Yet another exemplary embodiment relates to a method of operating a display system. The display system includes a light source and a filter. The method includes providing light from a light source in a first path including the filter when an electronically controlled mirror is in a first mode of operation, and providing the light from the light source in a second path not including the filter when the electronically controlled mirror is in a second mode of operation.
Yet another exemplary embodiment relates to an avionic display system. The avionic display system includes a light source. The avionic display system includes a means for providing a visual image, means for filtering light to attenuate at least a portion of the light associated with the visual image, and means for directing light from the light source. The means for directing directs the light through the means for filtering in a first mode of operation and directs the light to the means for providing a visual image without passing through the means for filtering in a second mode of operation.